Anaerobic Digest

BioCycle May 2014, Vol. 55, No. 4, p. 18

South Africa piggery powered by biogas from anaerobic digestion

Washington, DC: Application Period Open For Reap Funding

On May 5, the U.S. Department of Agriculture released up to $70 million in grants and loan guarantees through the Rural Energy for America Program (REAP). USDA uses REAP to fund a variety of energy projects on farms and at rural businesses, including biogas systems. About $12.4 million will be available for grants and $57.8 available for loan guarantees. Deadline for submission of an application is July 7, 2014 for grants, and July 31, 2014 for loan guarantees. Grant funds cannot exceed 25 percent of eligible project costs. Guaranteed loans cannot exceed 75 percent of eligible project costs. Combination guaranteed loan and grant cannot exceed 75 percent of eligible project costs. For renewable energy projects, the minimum grant is $2,500 and the maximum is $500,000. The minimum guaranteed loan is $5,000 and the maximum is $25 million. The funding comes from the Agricultural Act of 2014 (the 2014 Farm Bill), which was signed into law on February 7. In 2013, USDA funded 2,400 renewable energy and energy efficiency projects in rural areas. The link to obtain a REAP application is:

Cullinan, South Africa: Piggery Powered By AD Biogas

Swineline, a l,000-sow piggery, produces about 2.5 tons/day of manure. Odor control was the most significant environmental concern, leading Swineline to install a covered anaerobic lagoon to reduce odors and generate biogas that is fed to a Capstone 65 kW microturbine. The equipment began operating in December 2011. “The pigs stand on gridded floors that collect the waste,” says James Jenkinson, Swineline’s owner. “We flush that out with a volume of water that will then enter into the digester via the channels. Biogas goes into the gas treatment plant that prepares the gas as a fuel for the microturbine by taking out the condensate and also compressing the gas to a pressure that is acceptable for the turbine to operate. All the power we generate gets fed back into the piggery.”

The Capstone CR65 uses a Dual Mode Controller to facilitate protection of critical loads. Acting like an automatic transfer switch, the controller monitors incoming power and directs the microturbines to switch to stand alone operation when the grid fails. Protected loads see less than 10 seconds of outage during the transition from grid parallel to stand alone operation. “Installation of this turbine has reduced my electricity usage by a good 30 to 35 percent,” Jenkinson says. “The farm is a very small farm when you are looking at effluent production. We have only one turbine installed but by getting the process more efficient it could get to the point that I can reduce my electricity usage by even more.” He estimates that odor impacts on the surrounding community have been reduced by about 75 percent.

Costa Mesa, California: Curbside Organics To Digester Feedstock

Beginning in January 2015, residents of Costa Mesa, parts of Newport Beach and unincorporated Orange County, serviced by the Costa Mesa Sanitary District (CMSD), will no longer dispose of their household waste in a single cart. Residents will still have the luxury of commingling trash and recyclables, but organics — including food scraps and green waste — will be placed in a designated cart for processing at a new anaerobic digester to be owned and operated by CR&R in Perris, California. All food scraps, including meat, breads, produce and compostable bags, will be accepted. In a county where composting facilities are limited and landfill space is quickly disappearing, alternative means of managing waste are welcome. “We want to be in the frontline before everyone else is scrambling to figure out what to do with their organics and composting companies are being maxed out,” says Scott Carroll, CMSD General Manager, of the CMSD Directors’ unanimous decision to begin source separated organics recycling. “Plus the result is a marketable product.”

Hauling services for commingled trash/recyclables and organics will be provided by CR&R (using a separate truck for organics). CMSD estimates approximately 250 tons of organics will be collected for digestion weekly. In the current one cart system, residential waste and recyclables (including green waste) are separated at a transfer station. CMSD achieves a diversion rate of 57 percent, with most of the green waste used as alternative daily cover at landfills. According to Carroll, the diversion rate is expected to increase to 75 percent with the new collection service.

Changes in rates for residents will be minimal, he adds. CR&R has agreed to reduce rates for CMSD from $125/ton to $71.50/ton using public funds they received, including a $4.52 million grant from the California Energy Commission. As a result, residential fees will only increase by $1.91/month. A survey of 1,000 customers indicated that 41.4 percent of customers would be willing to pay more for collection services if it meant diverting more waste from the landfills. CMSD also held four town hall meetings and plans to involve the public in three more to communicate the changes and answer any questions before the new program starts. CMSD will also run public service announcements on TV and radio stations and update customers in its quarterly newsletter.

Durham, North Carolina: Duke Publishes Biogas Market Potential Report

In February, Duke University released a report titled, “Biogas in the United States: An Assessment of Market Potential in a Carbon-Constrained Future.” The report “…aims to answer the question of whether, and under what conditions, a substantial decentralized domestic biogas market could develop in the United States by 2040,” notes the Executive Summary. The authors developed supply and cost functions for biogas production facilities using landfilled waste, animal manure, wastewater sludge and biomass residue feedstocks, based on a number of assumptions and calculations that included detailed cost, feedstock and technology data. Using this information combined (total supply and cost estimates), the data generates feedstock and technology pathway-specific supply functions that when aggregated, produce a single national biogas supply function.

Significant findings of the report include: 1) Generation of biogas could be expanded to 3 to 5 percent of the total natural gas market at projected prices of $5 to $6/MMBtu; 2) Biggest potential biogas source appears to be thermal gasification of agriculture and forest residues and biomass, and smallest is wastewater treatment plants; 3) When projected electricity and natural gas prices and value of offsetting energy purchases are factored in, biogas for electricity generation may be more profitable than supplying to pipeline; and 4) True rate and extent of biogas market diffusion will depend on how electric power and gas markets evolve and on the specific design and implementation of future policy initiatives used to favor one product over the other (biogas for pipeline versus electricity). To read the full report, visit the “Publications” section of the Duke Nicholas Institute for Environmental Policy Solutions website, or find the direct link in the online version of this item.

Burlington, Vermont: Organic Waste To Vehicle Fuel

In late April, BioCycle attended a one-day workshop at the University of Vermont (UVM) titled “Cow Power: Turning Organic Waste into Vehicle Fuel for Vermont.” Stakeholders from the organics recycling, agriculture and energy sectors, including government employees, local anaerobic digester developers/operators, utility companies, and nonprofit entities, came together for the event, organized by Energy Vision — a nonprofit based in New York City focused on creating renewable energy from organics — in conjunction with the UVM Transportation Center and the Vermont Clean Cities Coalition. The workshop is one of many that Energy Vision is organizing across the country to promote its latest publication, “Turning Waste Into Vehicle Fuel: Renewable Natural Gas (RNG), A Step-By-Step Guide for Communities.

The April workshop was filled with presentations, panels and networking breaks, culminating with a discussion on policies that could promote use of renewable natural gas for vehicle fuel. Highlights included: an opening address by Chuck Ross, Secretary of the Vermont Agency of Agriculture, Food, and Markets on the importance of anaerobic digesters in increasing the financial viability of Vermont farms; an overview by Dan Smith, President of Integrated Energy Systems, on his AD project that involves generating renewable natural gas on an Addison County farm to be piped to Middlebury College, where it will replace #6 heating fuel for the campus; and Josh Kelly of the VT Agency of Natural Resources (VT ANR), who spoke on the passage of Vermont’s “Universal Recycling Law,” as well as the new organics map the agency is producing to help identify sources of organic feedstocks in the state. For more information on future workshops and how to purchase Energy Vision’s newest report, visit

Mills River, North Carolina: LEED Gold Digester For Sierra Nevada

In January, on 190 acres along the French Broad River about 20 minutes from Asheville, Sierra Nevada Brewing inaugurated a LEED Gold two-stage anaerobic digester, an integral part of its brand new East Coast brewery. (See “Anaerobic Treatment, Fuel Cell At Brewery,” January 2009 for a description of the digester installed at the company’s first brewery in Chico, CA.) Constructed by Milwaukee-based Symbiont Science Engineering & Construction, the Anaerobic Contact Sequencing Batch Reactor (ACSBR) treats over 220,000 gallons/day of wastewater and yeast (based on production of 700,000 barrels of beer per year). Wastewater and yeast enter a two-stage anaerobic equalization/hydrolysis tank to maximize biogas production in the ASCBR (second phase). Digested effluent flows to a post aeration tank prior to being discharged to the municipal sewer. The gas is fed into a biogas compression skid (with an emergency flare). A portion of the biogas is delivered at 90 psi to 200-kW Capstone microturbines; power is fed into the grid. Conditioned biogas also goes to the brewery boilers to heat the brewery, and to the brewery’s wastewater treatment plant boiler to provide heat to the digester. “It is supplying nearly all of the power needed to run the wastewater treatment plant,” says Tom Bachman, Symbiont’s vice-president of sales and marketing.

The ACSBR technology is proving exceptionally efficient, he adds. Incoming BOD and COD are 6,900 mg/L and 14,600 mg/L respectively, and total suspended solids is 14,600 mg/L. The treated wastewater meets the municipal sewer surcharge limits of 210 mg/L on BOD and 210 mg/L TSS. In addition, typical brewery treatment systems have a micro-screen prior to anaerobic treatment to further remove solids after grain has been separated out, explains Bachman. “We designed the system so that we could put in a [micro-]screen, but in 6 months of operating we have not noticed any need. In addition, after six months, we have only 4 feet of active bacteria and the tank can go up to 16 feet, so we don’t expect to have to clean out any bacteria. It is just digesting those solids.”

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